There have been already developed and used various kinds of devices which can be turned on or off with a foot switch and in which the work speed can be controlled with the foot switch. Such foot-switch-operated devices are essential when the user's hands need to be used for other tasks or when a user is not permitted to simultaneously use the feet and the hands for safety purposes.
For example, during the process of a modern surgical operation such as a laparoscopic operation or an ophthalmic operation, a foot switch is additionally operated by a surgeon to cause various kinds devices to perform different functions thereof.
Conventional foot switches are disclosed in U.S. Pat. Nos. 6,132,313 and 5,787,760. The foot switches disclosed in these patents have two rotational degrees of freedom (pitch and yaw) and can make forward and backward movement. However, they are structurally complicated and bulky. In case of the foot switch of the '313 patent, it is necessary to use two different pivot elements because the axes of yaw and pitch are not aligned with each other. An additional space is also required to permit the forward and backward movement. In case of the foot switch of the '760 patent, linear guides have to be used in order to accurately control the movement. Also required is an additional space to permit the forward and backward movement.
A need has existed for a pedal input device capable of easily realizing three degrees of freedom, while enjoying a simplified structure and a reduced volume.